1. Field of the Invention
The present invention relates generally to (i) an electronic device that runs a process to receive external wireless data and adjust operation based on the received data, (ii) a reception control method for the electronic device, and (iii) a reception control program for the electronic device. More specifically, the device, which may be a radio-controlled timepiece, is configured to adjust the time by receiving time information from an external source, while the reception control method and program are designed to carry out such the time adjustment operation.
2. Description of the Related Art
Electronic devices that receive wireless data from an external source and adjust operation accordingly, such as radio-controlled timepieces that receive time information from an external source to adjust the time, are known.
Such a radio-controlled timepiece has an antenna for receiving time information from an external transmitter, a receptor for processing information received through the antenna, memory for storing information from the receptor, a stepping motor driven and controlled according to stored time information, and hands that are moved by the stepping motor to indicate the time.
Thus configured, a radio signal carrying precise time information is received through the antenna. This time information is then processed (amplified and demodulated, for example) by the receptor, and a time information series is stored to memory. Stepping motor drive is controlled based on the stored time information, and the precise time is indicated by the rotationally driven hands. Because this operation is performed automatically, radio-controlled timepieces are extremely convenient.
In order for a radio-controlled timepiece to accurately adjust the time, it must accurately receive time information from an external source. A problem, however, is that the time information cannot be accurately received if a magnetic field surrounds the antenna of the radio-controlled timepiece. This is because the magnetic field interferes with the radio signal carrying the time information, and the waveform of the time information signal is distorted.
If the timepiece is stationary like a wall clock, this can be handled by locating it in a place that is not easily subject to magnetic field influences. However, if the timepiece is normally mobile, like a wristwatch, the problem of being unable to avoid the effects of magnetic fields remains.
A radio-controlled timepiece with an internal electromagnetic generator that is not subject to the effects of electromagnetic noise from electromagnetic power generation has been previously proposed. (see, Japanese Patent Laid-Open Publication (kokai) 2001-166071).
This radio-controlled timepiece with internal electromagnetic generator is a radio-controlled timepiece as described above additionally having a generator for generating electricity through electromagnetic generation, a power generation state detector for detecting the generating state of the generator by current detection, and a reception prohibiting unit for prohibiting reception based on the detection signal from the power generation state detector.
With this configuration the generation state detector detects the power generating condition of the generator. If power generation is detected, a detection signal is output from the generation state detector and time information reception is prohibited. Time information is therefore not received while electromagnetic noise produced by the generator producing electricity is present. Time information is received only when the generator is not generating and electromagnetic noise from the generator is not present. The time information can therefore be accurately received at select times, and the radio-controlled timepiece can accurately adjust the time when the time information is received.
The source of magnetic fields around the antenna of the radio-controlled timepiece is not, however, limited to an electromagnetic generator built in to the radio-controlled timepiece. Magnetic fields are also produced by, for example, brightness controls for lights and temperature controls for electric blankets, as well as common household appliances.
One problem is that the radio-controlled timepiece with an internal electromagnetic generator and a corresponding state detector cannot handle magnetic field sources outside the radio-controlled timepiece. More specifically, the generation state detector operates by detecting current from the internal generator, but cannot recognize external magnetic fields. The time information reception operation could therefore be carried out while influenced by an external magnetic field, in which case the time may well be incorrectly adjusted.
This problem is not limited to radio-controlled timepieces, and is common to electronic devices that receive external wireless information to perform some other process.